Links of platelet glutamate and glutathione metabolism with attenuated positive and negative symptoms in depressed patients at clinical high risk for psychosis

Aim of the study is to reveal clinical and biological correlations in patients with adolescent depression and attenuated psychotic symptoms. Activity of platelet enzymes involved in glutamate-, glutathione- and energy metabolism was evaluated in control group and in the patients, because these systems are suspected as related to pathogenesis of psychosis. Adolescents (78 men, 16-25 years old) hospitalized with the first acute depressive state composed two groups: with prevalence of attenuated psychotic positive or negative symptoms (Gr1 and Gr2, 48 and 30 patients, respectively). Control group comprised 20 mentally healthy men of 19-25 years old. Gr1 differed significantly from Gr2 in scores by the Scale of Prodromal Symptoms (SOPS) for positive symptoms, p < 0.001, for disorganization symptoms, p < 0.003, and for total SOPS score, p < 0.001, before the treatment started. When patients from either Gr1 or Gr2 were compared with the control group, significantly decreased baseline activities of platelet glutamate dehydrogenase (GDH), glutathione reductase (GR) and glutathione S-transferase (GST) were found (p < 0.0001). Different correlations were found between baseline enzymatic activities in Gr1 and Gr2: GDH activity correlated with GR activity in Gr1 (R = 0.37), and with GST activity in Gr2 (R = 0.70). Significant correlations were found only in Gr2 between the delta of scores by SOPS negative symptoms (SOPS-N) under treatment and baseline GDH, GST, and GR activities (R = - 0.36, R = - 0.60, and R = 0.38, respectively). The found correlations of the baseline enzymatic activity levels with the value of the decrease (delta) in SOPS-N scores under the treatment represent interest for the prediction of the pharmacotherapy efficiency.

[The link of platelet cytochrome C-oxidase activity with some clinical parameters of depression in elderly patients]

OBJECTIVE

To search for correlations between platelet cytochrome c-oxidase (COX) activity and the quality of therapeutic outcomes and other clinical parameters of depression in elderly patients.

MATERIAL AND METHODS

Twenty elderly women, aged 55-78 years, with depressive episodes in recurrent depressive disorder (RDD) or bipolar affective disorder (BD) were studied. COX activity and severity of depression were evaluated twice: before the beginning of antidepressant treatment and at the 28-th day of the therapy, using the Hamilton Depression Rating Scale (HAMD-17) and the Hamilton Anxiety Rating Scale (HAM-A).

RESULTS

Significant correlations were revealed between platelet COX activity and some clinical parameters of the disease and the severity of depression in patients after treatment. The baseline level of the platelet COX activity was correlated with the age of disease onset (R= -0.63, p=0.003) and its duration (R=0.55, p=0.010). Significant negative correlations were also found between the baseline level of COX activity and depression severity (HAMD-17 total score) (R= -0.48, p=0.032) and the severity of anxiety (HARSHAM-A total score) (R= -0.54, p=0.010) after 28-day treatment.

CONCLUSION

This pilot study has revealed a link between platelet COX activity and the severity of depression and anxiety after a 28-day antidepressant therapy. The results indicate the prospects for further study of COX as a biomarker of therapeutic outcomes in elderly patients with depression.

Decrease in 130 kDa- amyloid protein precursor protein (APP) and APP protein ratio in schizophrenia platelets

Cognitive dysfunction is common among people with schizophrenia. The molecular substrates underlying this remain poorly understood. To address this, we analyzed changes in amyloid precursor protein (APP) in platelets of people with acute schizophrenia (n=24) and control subjects (n=20) by ECL-immunoblotting. APP bands corresponding to molecular masses of ∼130, ∼110 and ∼100 kDa, and the APP ratio (APPr: highest APP molecular mass vs lowest APP molecular mass bands) were quantified. The intensity of 130 kDa-APP and the APPr were significantly reduced in schizophrenia patients compared to control subjects. The age-associated decreases in the 130 kDa, ∼110 kDa proteins and APPr were present in patients, but not controls. Our results confirm peripheral APP metabolism is altered in people with schizophrenia. Further work is now warranted on a larger sample of diseased subjects with detailed cognitive assessment to determine the APP role in cognitive processing in schizophrenia, how it is related to severity and disease progression, as well as outcomes.